Soak the Nuts at each end of the cat and the bolts fixing the exhaust hangers in PlusGas , WD40, or the like.

leave overnight

Often easier to unbolt the 17mm nuts on the inlet side of the cat as they tend to be less rusted, the cat and siliencer can bet seperated more easily once the exhaust system is off the car.

Put a jack or axel stand under the exhaust so it doesn't fall on your face.

Remove the three exhaust hanger rubbers - two 13mm AF nuts on each

The exhaust and cat should now be free.

seperate the cat and silencer

If you bought new 10mm bolts you can press out the studs from the ends of the cat using a heavy vice and an old socket.

copper grease everything liberally before putting it back together.

S2

TOOLS

Penitration Oil or WD40

This will help remove those very rusted bolts

Copper Grease, useful but not necessary

This should be used to coat all new bolts and nuts to prevent seizure in the future.

ratchet set

This is a must have item.

I also recommend a stainless steal bolt/gasket set from eliseparts that contains

6x Stainless Steel M10 bolts

12x Stainless steel M10 washers

6x M10 Stainless Steel full nuts

2 x new Exhaust Gaskets.

FITTING

New rubber exhaust mounts are a wise replacement as well
( 3 rubber mounts are used, 2 on the 'back box' and 1 one the CAT).

You may have to 'cut' off some of the old rusted bots, this is quite common.

Another recommendation of mine is to undo the top bolt in the left hand side of the wheel arch so you can disconnect the Lambda sensor wire and 'drop' it through the flap. (this is because the 22mm Lambda bolt on my exhaust would not come undone.) so you may not have to do this.

Soake the exhaust bolts over night, this should help the free-up some of the rusted bolts.

Soked bolts

I used a good half a can on the bolts by soaking them and leaving for half an hour or so then and re-soaking them.

It can help to remove the nearside rear wheel, inorder to gain access to the back of the cat bolts. You will also be able to get better leaverage from here.

I forgot to take pictures / get my camera out when i was using a friends hydraulic ramp as it was a bit hectic, but i did take some with my camera phone, sorry

Always good to have a friend, who is a 'grease monkey' near buy

Lambda Sensor

Lambda Sensor

Flexi Section of the Sports Cat

Sports Cat Fitted

Sports Cat Fitted

Elise Exhaust Mounts

Exhaust finnaly out

I would also like to say that on a scale of 1 to 10 ( 10 being a qualified mechanic). I am about a 2 (knowing little) and i think that changing the exhaust on the elise is easy, if you exclude the rusted/seized nuts that are more of a pain than a problem.